1. Field of the Invention
The present invention relates to a process for preparing flexible polyurethane foams which possess flame retarding properties.
2. Description of the prior Art
Thus far, polyurethane foams have been utilized as materials for routine use, such as, domestic funiture and cushions for vehicles due to their excellent cushioning properties. However, their use was restricted because of their lack of flame retarding properties. To avoid this handicap, investigations were made to provide polyurethane foams with flame retarding properties. This can be done by adding a large amount of flame retardant compounds, such as, compounds of phosphorus and halogens, either alone, or in combination to such foams. However, the foams thus treated evolve a large amount of smoke on combustion. The evolved smoke may cause serious disasters during fires. Thus, there is a general trend to regulate the smoke generation of vehicle and construction materials on combustion.
The present inventors, through extensive investigations on this point, have succeeded in producing flame retarding polyurethane foams which generate little smoke on combustion.